Question

Решить систему x-y=63 x+y=7

Answer 1

$left { {x-y=63} (1) atop {x+y=7}(2)} right. \ 1) x=y+63 \ 2) (y+63)+y =7 \ 2y = -56 \ y= -28 \ x= -28 +63 = 35 \ (35; -28)$